My truck is rated at 9900 pounds. My trailer is either 6800 or 7800 pounds loaded. Can't remember which, but its one of those. Even if I carried an extra 1000 pounds of gear, which I don't think I even come close too, at worst I'd be 8800.
Everybody I've talked to has told me that truck should pull the hell out what I've got and I think the same. But it just isn't doing it. The slightest grade in the road, I mean the slightest incline causes my truck to jump up to about 4700-4800 rpms to make any progress. I don't think letting my truck crank that much for extended periods is a good thing. I usually get off the gas and let it down shift and then try to give it as light a pedal as possible at which point I'm just barely moving. If I give it just a little bit of gas pedal it'll downshift againg and bang right up to 4800 rpms. Its frustrating as hell not to mention the 6.9 miles to the gallon I'm getting.
As far as I can tell the truck is in great shape. It runs great, I use synthetic motor oil, always change it around 3000 miles. Do all the prevenative maintainance on the diffs and trans and t-case. I don't know. I've recently done the exhaust, throttle body spacer and air intake. I've got some more low end out of it but thats all.
I use the tow/hual feature on the truck. It sucks to be shelling out all this dough to try and get out of the truck what I feel I should have been getting without any mods.